Woodland caribou restoration at Isle Royale National Park : A feasibility study

100 Pages·1996·4.9 MB·English

by  Cochran, J.

Woodland Caribou Restoration
at Isle Royale National Park
A
Study
Feasibility
Jean Fitts Cochrane
Technical Report NPS/NRISRO/NRTR/96-03
1
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United States Department of the Interior • National Park Service
Great Lakes Cluster • Isle Royale National Park
The National Park Service disseminates the results ofbiological, physical, and social science research
through the Natural Resources Technical Report Series. Natural resources inventories and monitoring
activities, scientific literature reviews, bibliographies, and proceedings oftechnical workshops andconfer-
ences are also disseminated through this series. Documents in this seriesusually contain information ofa
preliminary nature and are prepared primarily for internal use within the National Park Service. This
information is not intended foruse in the open literature.
This report comprises workcompleted in December 1992.
Mention oftrade names orcommercial products does notconstituteendorsement orrecommendation for
use by the National Park Service.
The cover illustration is a photograph ofthe painting. Caribou at Middle Islands Passage, Isle Royale, by
MN
Howard Sivertson, Box 397, Grand Marais, 55604.
Copies ofthis report are available from the author:
Jean Cochrane
Conservation Biology Program
University ofMinnesota
00 Ecology Building
1
1987 Upper Buford Drive
MN
St. Paul, 55108
Woodland Caribou Restoration
at Isle Royale National Park
A Feasibility Study
Jean Fitts Cochrane
Isle Royale National Park
800 East Lakeshore Drive
Houghton, Ml 49931
Present address:
Conservation Biology Program
University of Minnesota
100 Ecology Building
1987 Upper Buford Drive
St. PauLMN 55108
Technical Report NPS/NRISRO/NRTR/96-03
September 1996
United States Department of the Interior
National Park Service
Natural Resource Program Center
Natural Resource Information Division
Denver, Colorado
Digitized by the Internet Archive
in 2012 with funding from
LYRASIS Members and Sloan Foundation
http://archive.org/details/woodlandcaribourOOfitt
Epigraph
"Here [at the Island Mine spring in August of 1918 whetherthere are seven ornine calves. It may be
or 1919] is where I first met the Isle Royale cari- somebody has seen abettersection ofthe Isle
bou. I had found their tracks at two or three points Royale caribou herd, but I have neverheard them
along the trail that morning and only afew minutes tell ofit."
before had noticed that thejuice was still flowing
from abitten milkweed. Then, rightat
the top ofthis rise, I rounded this little
curve, and down there, where that
rock lies by the road, some eight or
ten rods away, stood three splendid
young bulls, looking backto learn
whatfollowed them. Probably they
had neverseen a man before; at least
they had no slightest fear. I stood for
fiveminutes watchingthemandthen
walking forword [sic] until I had cut
thedistance in halfbefore they turned
and trotted over the little rise ahead.
When I had climbed that, they were
again looking back and waiting for
me. To see what they would do, I
yelled, buteven thenthey ran away
Woodland caribou swimming, Slate Islands, Ontario, Canada.
slowly, though I saw nothing more of Caribou are excellent swimmers and regularly swim between islands
them."
to seek refugefrom predators. Photograph: H.R. Timmermann,
Ontario Ministry ofNatural Resources.
"[Andthen watching fromthebeach
at Lake Desor, after a sunrise
swim]. ... A halfmile away, headed
—
fromthe largest island, where they havebeen W.RF. Ferguson, "Wildlife and Adventures
spending the night, perhaps tokeep thecalves Along the Great DesorTrail on Isle Royale,"
secure from attackby the wolves1", aline ofcaribou DetroitNews, 28 May 1922
is swimming toward the main shore. Noses up,
antlers lying backalmostupon theirshoulders (the
cows have antlers as well as the bulls) with the
calves swimmingbravely alongsidetheirmothers,
they make a swiftpassage; and we see themclimb
the bank, theirdripping forms sharply outlined
against the green background. We count afull
baker's dozen ofthe adults and are a little in doubt
1 A popularterm forthe coyote (Cants latrans) in those days was "brush wolf.'

1 51 1 2 1
Contents
Listof Figures \ vii
ListofTables \ vii
Acknowledgments \ ix
Summary \ xi
Introduction \ 1
Study Objectives \ 2
Background \ 2
Isle Royale National Park \ 2
Caribou Distribution andDecline in the Lake SuperiorRegion \ 5
Caribou on Isle Royale \ 1
Methods \ 9
Results and Discussion \ 1
Why Did Caribou DisappearFrom Isle Royale? \ 1
Migration \ 1
Disease \ 1
Competition with Moose \ 1
Predation \ 13
Overhunting \ 14
Fires \ 14
Summary
\ 1
Habitat Suitability \ 15
ForageResources \ 15
Predators \ 21
Winter Ticks \ 22
Escape Habitat \ 23
Summary 26
\
Population Vulnerability Analysis \ 27
VORTEX
Results \ 27
Lessons From Elsewhere \ 28
Summary \ 29
ReestablishmentMethods \ 29
Alternative Reestablishment Strategies \ 30
Release Timing \ 30
Disease andParasit—e Screening \ 30
Sources ofCaribou the Slate Islands \ 31
Summary \ 33
Impacts and Management Implications \ 33
Vegetation \ 33
EndangeredSpecies andRare Plant Communities \ 33
OtherAnimals \ 34
Diseases andParasites \ 34
Wilderness \ 35
Summary \ 36
Conclusions \ 39
LiteratureCited \ 43
Postscript \ 53
Appendix A: Summary ofCaribou and Selected ReindeerTranslocation Attempts \ 55
LiteratureCited \ 57
Appendix B: VORTEX: Simulation Model ofStochastic Population Change \ 59
Stochastic Simulation ofPopulation Extinction \ 59
LiteratureCited \ 61
Appendix C: The History ofCaribou in the Lake Superior Region \ 63
Mainland Michigan (ExcludingIsle Royale) \ 63
Northeastern Minnesota \ 63
NorthwesternOntario \ 65
IsleRoyale \ 67
Appendix D: Caribou Ecology \ 73
Habitat Use \ 73
HomeRangeand Density \ 75
Escape Habitat and Predator Densities \ 76
Diet \ 77
Population Dynamics \ 77
Appendix E: Summary ofVORTEX Modeling Runs \ 79
Contents
6
Figures
—
Epigraph Woodlandcaribou swimming \ iii
1. Location ofIsle Royale National Park \ 2
2. Topography ofIsle Royale \ 3
3. Moose and wolfpopulations on Isle Royale \4
4. Isle Royale National Park map \ 5
5. Range limits ofcaribou in the Great Lakes region \ 6
6. Relict and introducedcaribou around Lake Superior \ 7
7. Woodland caribou crossing afrozen lake \ 11
8. Caribou hunters on north shore ofLake Superior \ 14
9. Vegetation type map ofIsle Royale National Park \ 1
10. Savanna habitat nearWindigocreated by intensive moose browse \
11. Lightly browsed habitat on Smithwick Island \ 18
12. Bog on Raspberry Island \ 19
13. Jack pine stand with ground lichens, Saginaw Peninsula \ 19
14. Spruce-fir forest on Mott Island \ 20
15. A pairofwolves on shore ice, Isle Royale \ 21
16. Majoroffshore isletgroups, Isle Royale \ 24
17. Rock Harborchannel in winterwith extensive icecover \ 25
18. Capturing woodland caribou on the Slate Islands \ 32
19. Preparing caribou for transport offthe Slate Islands \ 32
—
Postscript Female woodland caribou \ 53
Tables
1. Isle Royale vegetation and nonvegetation covertypes and areascovered \ 17
2. Offshore islets, Isle Royale National Park \ 24
3. Simulatedpopulation persistencetimes \ 28
VORTEX
4. Population values in simulations \ 80
5. Mortality rates by sex and age class \ 81
6. Woodland caribou population simulations run in VORTEX \ 82
7. Sample VORTEX results, run number4 \ 83
Contents